1. Field of the Invention
This invention relates to the art of stirring of contents of a container and more particularly to an improved motive force to produce the stirring action.
2. Description of the Prior Art
From the time cooking in a container over a fire was invented, a need to stir the contents thereof has existed. Early implements as a stick, paddle, spoon or such have been used with great success if moved in the container at the appropriate time. The desired movement of the implements has been the source of creative configurations. Such configurations have employed manual or powered means to drive the stirring means. The powered means have usually relied on electrical power as the motive force to drive a motor or create a local magnetic field that have caused a stirring means to move.
Manual implements for pot stirring fill the "cooking" shops. Each type of cooking can be helped with a specialized implement from a wooden spoon to a wok spatula.
The profusion of electric mixers of different sizes and shapes and different modes of movement provide excellent sources for stirring means.
The stirring means has been formed into many shapes such as: a simple rod, a whip composed of a number of wire loops, a paddle with or without holes, a beater composed of two loops of ribbon steel, a set of beaters that intermesh, circular plates with vanes, and a dough hook.
The motion of the stirring means employed in the prior art has been circular, rotary, opposing rotary, one rotary with one stationary and planetary.
The drive train between the motive force and the stirring means has included a direct coupling, a gear train to increase or decrease the speed of movement of the stirring means at either a fixed or variable speed, and possibly a clutch mechanism set to decouple the stirring means from the motive force should the stirring means become jammed.
Containers for cooking have been sized and shaped in a plurality of combinations. The two basic types of containers have been those with a simple cover and those with a locking cover to allow cooking under pressure.
The actual integration of a stirring arrangement with a container has occurred primarily in the field of commercial food preparation or in the scientific laboratory where the benefit of scale allow the apparatus to be economically feasible. Home food preparation activity has been left to combine known inventions such as holding an electric mixer in a container.
The available container stirring arrangements have mostly relied upon electric power which by its nature requires safety of design to guard against injury when working with liquid and heat.
Accordingly, with such a wide variety of containers, lids, coupling means and stirring means the real innovation is to provide a new and useful form of motive power.
It has long been desirable to provide a stirring means for a container in which the entire arrangement can be placed over a source of heat for cooking without the danger of damage to an electric cord or the nuisance of continuous manual participation.
Accordingly, if a motive force that does not rely upon electricity could be combined with the stirring means, the safety impact of such an invention would be great.
The motive force for this invention is the expansion and contraction of a metal alloy as it is cycled through a temperature change. The usual manifestation of this property is expansion when heated and contraction when cooled. However, an alloy of nickel and titanium can be shaped to exhibit an opposite activity due to a crystalline phase change of the alloy. When the alloy is alternately heated and then cooled, the thermo gradiant can allow the nickel, titanium alloy to undergo a change of shape sufficient to produce a motive force.